The crystal structure and electronic properties of the complexes acetatobis(1,10-phenanthroline)copper(II) perchlorate dihydrate, acetatobis(1,10-phenanthroline)copper(II) nitrate dihydrate, and acetatobis(1,10-phenanthroline)zinc(II) tetrafluoroborate dihydrate

The crystal structure of [Cu(phen)₂(O₂CMe)][ClO₄]·2H₂O (1), [Cu(phen)₂(O₂CMe)][NO₃]·2H₂O (2), and [Zn(phen)₂(O₂(CMe)][BF₄]·2H₂O (3) have been determined by X-ray analysis. Complex (1) crystallises in the monoclinic space group P2/c with a = 9.671(3), b = 8.282(3), c = 17.595(4) Å, β = 109.63(2) °, and Z = 2; (2) crystallises in the triclinic space group P1 with a = 14.728(2), b = 10.499(2), c = 8.603(2) Å, α = 104.19(5), β = 83.97(5), γ = 96.81(5)°, and Z = 2;(3) crystallises in the monoclinic space group P2/c with a = 9.659(2), b = 8.262(2), c = 17.651(2) Å, β = 109.06(5)°, and Z = 2. The MN₄O₂ chromophore in all three complexes has a cis-octahedral stereochemistry. In (1) and (3) the metal atoms have C₂ symmetry and in (1) there is a marked cis distortion of the Cu-O distances. In (2) a distortion of the CuN₄O₂ chromophore towards a square pyramidal (4 + 1 + 1*) stereochemistry is present. The polycrystalline e.s.r. spectra of (1) and (2) and of 10% copper(II)-doped (3) are temperature variable, consistent with a fluxional CuN₄O₂ chromophore stereochemistry. The temperature variability of the single-crystal e.s.r. spectra of (1), (2), and copper(II)-doped (3) is restricted to the CuN₂O₂ plane, consistent with two-dimensional fluxional behaviour. The electronic reflectance spectra of (1) and (2) involve two peaks at ca. 10 000 and ca. 14 000 cm^-1 and relate to the underlying static CuN₄O₂ (4 + 1 + 1*) chromophore stereochemistry.